October 4, 2002

Dear Mr. Hailer:

Re: Illinois Central Spring Treatment
Facility (ICSTF), Bloomington, IN

Thank you for your letter of August 29, 2002, regarding the ICSTF. Indiana Department of Environmental Management (IDEM) staff have generated the following responses to your questions.

1. This issue has been addressed numerous times in previous letters. IDEM staff have never claimed that the overflow water from the tanks is "treated" to our discharge standard of 0.3 parts per billion (ppb).

Water enters the Spring Receiving Sump (SRS) Tanks from the bottom, and once the tanks reach capacity (which is approximately 1.2 million gallons), water overflows a weir at the top of the tanks. The design of the tanks allows them to act as a passive clarifier. It has been our experience at the ICSTF that inflows to the tanks enter with a measure of settleable solids and that the corresponding overflows are void of any such settleable solids. The term "clarified" is appropriately applied in this case. Accordingly, it is important that any such overflows be measured and recorded separately. The effect on polychlorinated biphenyl (PCB) removal or capture is not known at this time; therefore, it is of some importance to be able to track and account for the different flow streams.

2. The fire alarm system is very sophisticated and allows for a number of operational modes including the isolation of single sensors. The false alarms that have been reported possibly were caused by two different factors. The sensors currently use a photo ionization process to detect the presence of smoke across the unit. It appears that the units in question may alarm when there is fog from humidity in the immediate area. This may account for some of the false alarms. Corrosion of the unit may also be another cause of the reported problem. The faulty units have been replaced and the situation is resolved.

3. We have not determined the cause of the malfunction of the datalogger. The datalogger records information from the facility every 5 minutes, including all tank levels, flow measurements, and pressures. This data is used to tune, analyze and trouble shoot the various processes. For any given time or period, the data may be important depending on what process or problem is under review. As of this date, no information loss has caused an operational or analysis problem. We have changed our protocol to ensure the datalogger is checked every day.

4. All sampling at the facility is conducted according to the Sampling and Analysis Plan found in the Operations and Maintenance Plan for the ICSTF. Influent and effluent samples are collected weekly when storm sampling has not been conducted for the week. Storm samples include influent and effluent sampling. Water quality parameters are measured for effluent samples to ensure the effluent can support aquatic life.

Thank you for pointing out a portion of the Sampling and Analysis Sheet (SAS) that could be confusing. The "rainfall" column on the SAS represents rainfall between sampling events. The daily operation report can account for rainfall events each day, but the SAS cannot account for rain that may have occurred the day before the sample was taken. The "rainfall" column will be removed from the SAS sheet to eliminate confusion.

5. Our usual turn-around time for PCB water samples is seven days. Twenty-four hour turn-around time is not customary, prohibitively expensive, and not warranted based on the fact that effluent samples have historically been below the 0.3 ppb discharge criteria and more often non-detect at a detection limit of 0.1 ppb. Please see the U.S. Environmental Protection Agency's (EPA's) letter dated April 22, 2002, for a discussion regarding the use of the congener method of PCB analysis.

6. Personnel air monitoring at the facility has shown that worker exposure is below the National Institute for Occupational Safety and Health (NIOSH) exposure limit of one microgram per cubic meter (ug/m3) for an 8-hour work day, that includes regular visits to the SRS. The regulatory limit from the Occupational Safety and Health Administration (OSHA) is 1,000 ug/m3. To be conservative, however, the U.S. EPA is installing additional ventilation in the SRS. All workers are required to follow confined space entry procedures and wear a respirator when entering the lower sump in the SRS. The respirator requirement may be discontinued if the engineering controls are effective.

The perimeter air monitoring event conducted in April 2002 does not support your claim that the facility vents excessive PCBs to the atmosphere. Our air monitoring also does not support characterizing the exposure in the SRS as a "danger" to the operator.

7. The purpose of the tank drain valve is to allow only enough water to drain from the SRS tanks into the sump so that tank drainage plus spring flow equals 900 gpm. We allow a 100 gpm margin for fluctuations in measurement devices.

8. The water held in the SRS tanks for the calibration check was drained and the water processed through the facility by 11:30 AM on June 5. Rainfall began approximately 12:15 PM on June 5. Storm water storage began at approximately 3:00 PM. No water from the calibration check was overflowed from the tanks. The purpose of the calibration was to ensure the ultrasonic level meter that reads the water level in the tanks was reading properly after the meter was repositioned. The meter is functioning normally.

9. Plant capacity cannot be calculated on a monthly basis. Rainfall events are not evenly distributed throughout the month. The maximum capacity of the facility is 1,000 gpm, and during heavy rainfall, the spring can flow over 5,000 gpm. The excess spring water is sent to the SRS tanks for storage, and when storage capacity is exceeded, the water is overflowed from the top of the tanks. Please remember this plant is a pilot facility, and under review by the U.S. EPA and IDEM to determine if any additions or changes should be made when the facility is converted from a time-critical removal action to a permanent remedy.

If you have any further questions regarding this letter, please do not hesitate to contact me at (317) 233-2823.

Jessica Huxhold Fliss, Project Manager
Federal Programs Section
Office of Land Quality